Hitachi Hidic EH-150 Applications Manual page 51

Preliminary Rev.03
7.2 Presetting
Before the data communication, you have to establish connection against to the other port. Here after, an
enabled connection is called as "opened connection", and a disabled connection is called as "closed
connection".
7.2.1 Open connection
The procedure for opening connection is shown as fig.7.2.1.1.
Host PC
(A-2)
(A). In case of active open setting
EH-ETH requests active open against host PC of passive
(A-1)
open status.
Host PC receives the request to connect from EH-ETH,
(A-2) sends a reply of ready to open connection to EH-ETH, and
waits ACK from EH-ETH.
EH-ETH receives the reply from the host PC, and sends
(A-3)
back ACK.
Host PC requests active open against EH-ETH of passive
(B-1)
open status.
EH-ETH receives the request to connect from Host PC,
(B-2) sends a reply of ready to open connection to Host PC, and
waits ACK from Host PC.
Host PC receives the reply from the EH-ETH, and sends
(B-3)
back ACK.
The following procedure is required for each ASR connection.
(1). Select communication protocol
(2). Select active open or passive open
(3). Setting of own logical port number
(4). Select specified or optional other station.
(5). IP address of the other station (Only in case the other station is specified.)
(6). Logical port number of the other station. (Only in case the other station is specified.)
Description in this manual might be modified without notice.
EH-ETH
(A-1)
(A-3)
(A). In case EH-ETH is in active open
Description
(B). In case EH-ETH is in passive open
Description
Fig. 7.2.1.1 Basic procedure to open connection
7-4
Chapter 7 Automatic data transmission
Host PC
(B-1)
(B-3)
(B). In case of passive open setting
Segment
Sending SYN flag
Sending SYN ACK
flag
Sending ACK flag
Segment
Sending SYN flag
Sending SYN ACK
flag
Sending ACK flag
EH-ETH
(B-2)
EH-ETH status
Sending request to
connect
(SYN-SENT )
-
Connection opened
(ESTABLISHED )
EH-ETH internal
Sending request to
connect
(SYN-RCVD)
Connection opened
(ESTABLISHED )